Multiple feed system.



A. T. MARSHALL. MULTIPLE FEED 8Y8'1EM. I APPLICATIOI FILED JULY 30, 1910- H 1,003,233, Patented Sept; 12,1911.

ZZZ finesse i in 1/50 for 417M 1 MW UNITED STATESPATENTI OFFICE.

ALBERT T. 'MARSHALL, or rmn'rronn, cormrcrronr, Assienon To run nuroina'rrc nnrarenna'rme COMPANY, or HARTFORD, CONNECTICUT, a CORPORATION or NEW JERSEY.

MULTIPLE FEED SYSTEM.

Patented Sept. 12, 1911.

Application filed July 30,1910. Serial No. 574,683.

To all whom it may concern; 1

Be it known that I, ALBERT T. MARSHALL, a citizen of the United States, residing at- Hartford, in the county of Hartford and State of Connecticut, have invented a new and useful Multiple Feed System, of which I the following is a specification.

My invention relates to systems whereby expansive fluid is automatically fed'through one or more secondary chambers, especially those known as the expansion coils of refrigerating systems, in parallel with a primary or main chamber or coil, in response both to the thermal conditions around such one or more secondary chambers or coils and also to the pressure therein.

The purpose of my invention is to refrigerate one or more secondary compartments,

in parallel with a primary compartment, by.

a simple method of'control previous to and during the time the primary compartment is refrigerated in the usual manner.

The accompanying drawing represents a diagrammatic illustration of my invention.

Motor 1 is belt connected to a gas compressor 2, circulating refrigerant, preferably ammonia. The compressed gas is forced through a condenser 3 into a receiver 4, whence leads a feed pipe or main 5 which supplies a number of chambers in parallel as follows: 13 is the primary or main chamber which contains expansion coil 8 connected to high pressure main 5 with a socalled fixed back pressure expansion valvefi interposed. This valve maybe of the construction as shown in my U. S. Patent No. 785,265 of March 21st, 1905 or any other suitable construction. The characteristic feature of this typeof expansion valves is that they admit refrigerant to the expansion coil only when the pressure therein falls below a certain amount for which the valve is adjusted, so that so long as this low back pressure has not been reached in the coil no refrigerant is fed to this coil.- Coil 8 is connected at its other end to return main 9 which is connected to the compressor and forms the low pressure side of the system. Parallel to coil 8 are connected refrigerating coils 12, 12", 12 12 which are dis osed in what shall be termed secondaryre rig-crating compartments 13 13*, 13, 13 respec: tivelywhich may serve vdifferent purposes,

used for producing ice in' cans 18. Expan sion valve 10 is of the type set forth in the U. S. Patent to me dated August 8, 1899 No. 630,617, in which the refrigerant supply is controlled by the movement of a diaphragm one side of which is exposed to pressure fluid, the pressure of which is responsive to variations 'in temperature, its other side bein exposed to the back pres sure of the re rigerant. By properly ad-. justing 'aspring which counteractsv this controlling pressure as clearly described in said patent proper adjustment of the valve to suit the required conditions may be obtained, i

The temperature responsive fluid (preferably anhydrous ammoniayis inclosed in a cylinder 22 in each compartment, through which theend of its refrigerating coil passes before joining the return main 9. Each ammonia cylinder 22 is connected by-a pipe 19 with the expansion valve 10 of the re-i spective chamber so that the varying pressure of the ammonia charge in each cylinder is imparted to the diaphragm of its expansion valve as described in aforesaid patent. in the art, the expansion valve supplies all the refrigerant which the coil can evaporate so that at all times the whole length of the coil remains frosted and maintains uniform temperature over the whole length. While'by such thermostatic cylinders 22 in conjunction with the type of expansion valves 10 just described a vuniform temperature of the whole length of the expansion .0011 may be maintained, this manner of control does not furnish means for maintaining an exact temperature within narrow' limits in the refrigerating compartment itself, so that where such exact temperature- .may be required owing to the. purpose;

which the chambers" serve, as for instance chambers 13, '13", 13, I prefer to employ 110 By this arrangement as is well known v iii-addition to the thermostatic charge con- .desired moment. Now, in order to stop the operation of the compressor, primary chamber 13 contains an electrothermostat which is suitably connected (not shown) to the electromotor '1 so that when the temperature in chamber 13 has dropped to the desired degree the motor is stopped, and

'An arrangement of this kind is for 111?.

started again when the temperature rises.

stance clearly illustrated in the patent to Chamberlain and Marshall No. 834,870 of October 20, 1906. i

The whole arrangement of the system,

just described has theeffect that at a back pressure in the lowpressure side 9 of the system, above the pressure at which expansion valve 6 of primary chamber 13 supplies refrigerant, the secondary chambers alone first receive refrigeration according to their individual requirement and only as their refrigeration is gradually shut down; by the cooling. of their thermostatic charge in cylinder 22, and as thereby the back pressure in return main 9rfalls, expansion. valve 6 opens and supplies refrigerant to its coil 8.

The operation of the system is as follows: Assuming the/compressor stopped andtha-t all the chambers are warmed up. Thermostat 25 of the controlling or primary chamber then starts the motor and'the compressor commences to operate. The pressure in {the low pressure side 9 being then still very highval've 6 of the primary chamber does not open yet for the reasons previously explained. But the thermostatic expansion valves 10 of the secondary chambers supply their coils with all the refrigerant the coils can evaporate. Now the coils 12, 12*, 122-12 all discharging the maxi mum amount of vaporized refrigerant into the return main 9 the back pressure therein at first does not drop very much until the coils in these chambers commence to cool to thedesired degree, when the thermostatic charge at the end of each coil, cooled thereby, gradually reduces the refrigerant sup ply to its coil, so that now the back pres sure in main 9rapidly dropsuntil the point is reached when valve 6 opens and commences to supply refrigerant to its coil 8 in chamber 13. All the. ,other chambers are of course still supplied sufiiciently to maintain the pro er refrigeration, which may be obtained y properly adjusting expansion valves 10 with respect to the effect of the pressure of the thermostatic charge upon the valve diaphragm; but still the main work of the compressor at that period is done in the primary chamber 13 the frost in its coil 8 gradually creeping along to- Ward the end. This refrigeration continues until the desired temperature is reached at which thermostat 25 shuts down the motor. When the temperature in chamber 13 rises again the motor commences again to work. It may be pointed out that of course the system with respect to the capacity of the several chambers and refrigerating compartments is dimensioned so that when for instance the motor is shut down by thermostat 25 and the secondary chambers should require refrigeration, theywill not have to wait long until primary chamber warms up sufiiciently to start the motor, and in turn when the motor has thus started and supplies refrigerant to the secondary chambers first primary chamber 13 does not have to wait long until the back pressure drops to the pointat which valve 6 supplies the coil 8 with refrigerant. While in this system the chambers or compartments controlled by the thermostat valves 10 always have first claim on the refrigeration at high temperatures of the refrigerant in the coils, the system is unable to produce in the secondary chambers the extremely low temperatures and also. the extremely low back pressures in the return conduit which it would if the valves 10 were working without the fixed back pressure valve 6 in the primary chamber. The

reason why no extremely low temperatures can be produced in the secondary chambers is, that at no time the refrigerant in the coils of the secondary chambers expands into a very low back pressure, and thus cannot produce low temperatures; because when the low pressure point at which valve 6 opens is reached, this valve continues feeding the refrigerant, so that it thereby prevents the back pressure from fallin any appreciable degree below the point or which the valve 6 is set. Thus, valve 6 indirectly controls, to a certain extent, the lower limit of temperature in the secondary chambers.

It is of course obvious that the motor may also be. shut down by hand when a certain desired temperature has -been reached instead by the thermostat without departing from the spirit of my invention, electrothermostats of the kind as also shown in aforesaid patent to Chamberlain and Marshall being generally provided with means for controlling the motor by hand.

What I claim is:

1. A refrigerating system having a compressor for supplying refrigerant, a primary refrigerating compartment with an expansion coil therein and an expansion valve responsive to predetermined fixed back pressure only, at least one secondary compartment and an expansion coil therein in parallel to said primary coil, an. expansion valve for said secondary coil controlled by the temperature of a thermostatic charge at the end of the coil to causethe valve to feed all the refrigerant the coil can evaporate, said fixed. back pressure valve having means for adjusting it to only feed refrigerant when said secondary expansion valve is substantially closed by the action of its thermostatic charge. x

' 2. A refrigerating systemhaving a compressor for supplying refrigerant, a primary refrigerating compartment with an expansion coil therein and an expansion valve responsive to predetermined fixed back pressure only, at least one secondary compart ment and an expansion coil therein in parallel .to said primary coil, an expansion valve for said secondary coil controlled by the temperature of a thermostatic charge at the end of the coil to cause the valve to feed all the refrigerant the coil can evaporate, said fixed back pressure valve having means for adjusting it to only feed refriger ant when said secondary expansion valve is substantially closed by the action of its thermostatic charge, and means for stopping the operation of said compressor when the desired temperature in said primary chamber is reached.

3. A refrigerating system having a compressor for supplylng refrigerant, a primary refrigerating compartment with an expansion coil therein and an expansion valve responsive to predetermined fixed back temperature .of a thermostatic charge at the end of the coil to cause the valve to feed all the refrigerant the coil can evaporate, said fixed backpressure valve having means for adjusting it to only feed refrigerant'when said secondary expansion valve is substantially closed by the action of its thermostatic charge, and a thermostat for stopping the operation of said compressor when the desired temperature in said primary chamber is reached.

4. A. refrigerating system having a compressor for supplying refrigerant, a primary refrigerating compartment with an expansion coil therein and an expansion valve responsive to predetermined fixed back pressure only, at least one secondary compartment and an expansion coil therein in parallel to saidprimary coil, an expansion valve for said secondary coil controlled by the temperature of a thermostatic charge at the end of the coil to cause the valve to feed all the refrigerant the coil can evaporate, said fixed back pressure valve having means for adjusting it to only feed refrigerant when said secondary expansion'valve is substantially closed by the action ofits thermostatic charge, and a thermostatically con trolled stop-valve for said secondary chamher, to cut off the refrigerant when the desired temperature in the chamber has been reached.

ALBERT T. MARSHALL. 

